Inclusion Complex of Fexofenadine Hydrochloride with Cyclodextrins

Fexofenadine hydrochloride (FFN), (±)-4-[1-hydroxy-4[4-(hydroxydiphenylmethyl)-1-piperidinyl]-butyl] α,α-dimethylbenzeneacetic acid hydrochloride, is a second-generation antihistamine that is used to treat allergies. The drug is highly hydrophobic and slightly soluble in water. Cyclodextrins are widely used to improve the physicochemical and pharmaceutical properties such as solubility, stability, and bioavailability of poorly soluble drug molecules.Cyclodextrins can molecularly encapsulate various drugs into their hydrophobic cavity without forming any covalent bonds. Cyclodextrin (CDs), especially ß-Cyclodextrin (ß-CD), are widely used in the pharmaceutical field due to its ability to stabilize drug molecules and taste masking purposes. The phase solubility study was performed according to the method of Higuchi and Connors by adding the fexofenadine hydrochloride in excess to different concentrations of cyclodextrin solutions. Phase solubility study records show that the stability constant and complex stoichiometry of FFN-CD complexes increases linearly with CD concentration. Also, an increase in the concentration of β-cyclodextrin leads to an increase in the aqueous solubility of FFN. Complexes were analyzed by UV-VIS spectroscopy using the calibration curve of FFN. Also, UV-VIS spectra indicate a bathochromic shift which proves that complex formation has occurred.Solid inclusion complexes of fexofenadine/β-cyclodextrin and its derivatives were prepared at the molar ratios of 1:1 by the physical mixing method. Characterization of the complexes was performed by using infrared spectroscopy.